Practice Question: Shear Stress Comparison in Structural Steel Sections

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Solution

Answer: B) Option 2
For reference, beam shear stress is calculated as follows:

\[\tau = \frac{VQ}{Ib}\]\(V = \text{shear force}\)

\(Q = \text{first moment of area}\)

\(I = \text{moment of inertia}\)

\(b = \text{width of section}\)

For a wide flange beam, the maximum shear stress can be approximated as:

\[\tau_{max}= \frac{V}{A_{web}}\]\(A_{web} = \text{cross-sectional area of beam web}\)

Given that the box section has approximately twice the web area of the wide flange section, it can be deduced that Option 2 will have a lower shear stress.

 

 

 

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